Self-cocking, courtesy of Mershon & Hollingsworth
Here we see a rare prototype Colt Model 1860 Army Percussion Revolver with Mershon & Hollingsworth Cocking Device.
The Mershon and Hollingsworth used a wind-up spring to power a ratchet inside the hammer while a fold-out handle on the left side of the revolver’s frame was used in winding the spring. When wound and the trigger was pulled, the hammer fell, busted the percussion cap and ignited the charge in the chamber– firing the round.
Then– and here is where the magic occurred– a lug at the rear of the trigger slipped into the device and kept it motionless and when the trigger was reset, the lug backed out, allowing its spring to rotate an internal wheel (here is where the winding came in) that moved the hammer back to full-cock, and at the same time, unlocked, rotated, and re-locked the cylinder.
Seems like a lot of moving pieces to make the single action gun a very complex double action.
Description of this particular revolver as per the auctioneer via Collectors Books:
Serial no. 3803, .44 caliber. Standard cylinder and 7 ½-inch barrel with New York markings. Custom brass frame with case-hardened hammer and oil-finished walnut grips. Right side of frame with circular German silver fitting inscribed: Mershon & Hollingsworth/Sept. 8th 1863. Left side of frame fitted with wheel-shaped steel panel cocking device with folding rim. Evidently designed to create a self-cocking revolver similar to the later British Fosbery revolver. Rear of frame with fire-blued lever engaging the hammer and evidently serving as a safety. Elongated hammer. Condition: Fine. Barrel retains 90% plus blue finish mixed with brown patina. Cylinder retaining much blue finish. Estimate: $25000 – $35000